PROJECT SUMMARY HIV and injury are substantial public health problems, which disproportionately occur in low-and middle-income countries (LMICs); with the majority of morbidity and mortality levied in sub-Saharan Africa (SSA), in countries such as Kenya. Although HIV and injury are immense problems, there is a paucity of study of their intersection. Additionally, those most likely to need emergent injury care are young adults and males, key groups for HIV services that have not been adequately engaged in HIV programs in SSA. This epidemiologic concordance of injury in neglected HIV groups represents an opportunity to increase testing during the provision of commonly sought emergency care; a known period for personal health growth in young adults. However, as facility based opt-out HIV testing has been challenging in SSA, and Kenya specifically, novel approaches to improve testing among populations with unique needs are required. HIV self-testing (HIVST) is an innovative strategy, which is endorsed by the Kenyan Ministry of Health as a method to increase HIV care among high-risk groups, such as young adults and males, but has never been leveraged in SSA emergency care to enhance HIV testing. This research aims to address knowledge gaps in the study of HIV and emergency injury care in Kenya. The proposed work will generate robust quantitative and qualitative data on characteristics of emergency department (ED) HIV care as well as barriers and opportunities to care, and the use of HIVST to augment testing in the difficult to access young adult and male populations seeking treatments. Subsequently, implementation science using a hybrid implementation-effectiveness design, which has not been employed prior in SSA acute care research, will be used to efficiently evaluate the innovative delivery of ED based HIVST among patients and providers. These studies will provide crucial foundational data for future large-scale multi- site implementation trials which will inform global policy on the interface of HIV and emergency care in SSA as well as the use HIVST to enhance care delivery in previously missed LMIC populations (i.e. young males). My long-term career goal is to become a highly trained clinician scientist with expertise in implementation research and the study of the intersection of HIV and emergency care in LMICs. With the attainment of training and mentorship through this K23 award, in conjunction with my prior HIV and emergency care research experiences; I will be able to succeed in that trajectory. My career development aims for this proposal are to gain in-depth training in implementation science and mixed methods research while generating innovative data at the intersection of HIV, emergency care and ED-HIVST. Activities from this proposal will facilitate my transition to being an independent investigator able to design and lead future research studies that will evaluate the impacts of HIVST and additional ED interventions on testing and linkage to care of index patients and social / sexual contacts using implementation science trials, complemented by qualitative methods, to contribute to informing and improving HIV programming in high-risk LMIC populations.